Portable apparatus for generating electrical energy

Abstract

A portable apparatus if provided for generating electrical energy. The apparatus has an electrical energy-generating device for generating electricity in response to input mechanical action, and a gravity powered drive for supplying the said mechanical action to the electricity-generating device by the descent of a suspended mass under the force of gravity. A protection system is provided to prevent a drive force, experienced by the electrical energy-generating device due to the input mechanical action, from exceeding a predetermined threshold as a result of an overload condition. The protection system may perform the dual function of physically protecting the electrical energy-generating device whilst also providing clear feedback to the user that the apparatus is subjected to an undesirable overload condition.

1 . A portable apparatus for generating electrical energy, the apparatus comprising:
 a. an electrical energy-generating device for generating electricity in response to input mechanical action;   b. a gravity powered drive for supplying the said mechanical action to the electricity-generating device by the descent of a suspended mass under the force of gravity;   c. a protection system adapted to prevent a drive force experienced by the electrical energy-generating device due to the input mechanical action from exceeding a predetermined threshold as a result of an overload condition.   
     
     
         2 . An apparatus according to  claim 1 , wherein the electrical energy-generating device comprises a gear train for converting a relatively low speed input from the gravity powered drive to a relatively high speed output. 
     
     
         3 . An apparatus according to  claim 1 , wherein the electrical energy-generating device comprises an electrical generator selected from the group comprising an alternator, a direct current motor or a dynamo. 
     
     
         4 . An apparatus according to  claim 1 , wherein the overload condition is representative of one or more of the application of a mass in excess of a predetermined magnitude or the uncontrolled descent of the mass. 
     
     
         5 . An apparatus according to  claim 1 , wherein the protection system at least partially mechanically decouples the mechanical drive from the electrical energy-generating device. 
     
     
         6 . An apparatus according to  claim 1 , wherein at least part of the protection system is positioned between the gravity powered drive and the electrical energy-generating device. 
     
     
         7 . An apparatus according to  claim 1 , wherein the protection system comprises a frictional mechanism for causing a reduced drive force to be provided to the electrical energy-generating device during the overload condition. 
     
     
         8 . An apparatus according to  claim 7 , wherein the frictional mechanism is a clutch or brake. 
     
     
         9 . An apparatus according to  claim 1 , wherein at least part of the protection system is positioned at or adjacent a coupling point of the mass. 
     
     
         10 . An apparatus according to  claim 1 , wherein the apparatus has a housing comprising an attachment member for attaching the apparatus to a support when in use, and wherein at least part of the protection system is positioned at or adjacent the attachment member. 
     
     
         11 . An apparatus according to  claim 1 , wherein the protection system comprises a resiliently biased member. 
     
     
         12 . An apparatus according to  claim 1 , wherein the protection system further comprises an extendable coupling comprising a coupling housing and a length of flexible material, configured to allow the controlled separation of a first part of the apparatus attached to one end of the flexible material with respect to a second part of the apparatus attached to the coupling housing in response to the overload condition. 
     
     
         13 . An apparatus according to  claim 12 , wherein the extendable coupling further comprises a clutch which causes the flexible material to be deployed when in the overload condition. 
     
     
         14 . An apparatus according to  claim 12 , wherein the extendable coupling comprises a spool of the flexible material. 
     
     
         15 . An apparatus according to  claim 1 , wherein the protection system comprises protection circuitry electrically connected to the output of the electrical energy-generating device, the protection circuitry being configured to operate when in the overload condition so as to reduce the electrical load on the electrical energy-generating device thereby allowing the electrical energy-generating device to operate at a speed in excess of that at which it operates under normal conditions. 
     
     
         16 . An apparatus according to  claim 15 , wherein the protection circuitry comprises a switch and a warning device connectable to the output of the electrical energy-generating device in response to the switch being operated. 
     
     
         17 . An apparatus according to  claim 16  wherein the warning device is series connected with a resistor. 
     
     
         18 . An apparatus according to  claim 16 , wherein the switch is operable to connect the warning device to the electrical energy-generating device when in a first position and the switch is adapted to adopt the first position when the apparatus is in an overload condition. 
     
     
         19 . An apparatus according to  claim 8 , wherein the switch is operable to connect an operational circuit to the electrical energy generating device when the switch is in a second position. 
     
     
         20 . An apparatus according to  claim 15 , wherein the protection circuitry comprises a zener diode and a warning device connected to the output of the electrical energy-generating device. 
     
     
         21 . An apparatus according to  claim 20 , wherein the protection circuitry is adapted such that current is caused to flow through the protection circuitry when an electrical potential difference across the electrical energy generating device exceeds a predetermined threshold. 
     
     
         22 . An apparatus according to  claim 20 , further comprising a switch operable to connect an operational circuit to the electrical energy generating device. 
     
     
         23 . An apparatus according to  claim 16 , wherein the protection circuitry comprises a warning LED and/or buzzer so as to signal the existence of the overload condition to the user. 
     
     
         24 . An apparatus according to  claim 15 , wherein the protection system comprises a member which moves physically in the event of an overload condition and causes the operation of the protection circuitry. 
     
     
         25 . A portable apparatus according to  claim 1 , wherein the electrical energy-generating device and gravity powered drive are provided as a unit, the gravity powered drive including a flexible sprocket belt to one end of which is coupled the weight when in use so as to provide the force for operation of the apparatus. 
     
     
         26 . A kit comprising:
 a. a portable apparatus according to  claim 1 ,   b. a sprocket belt to form part of the gravity powered drive; and   c. a primary weight bag and a counterweight bag for attachment to respective ends of the sprocket belt.